Currently, only two types of walkways are being installed on single ply roofing: (1) solid concrete slabs or stepping stones which are laid without adhesive on the roof membrane; and (2) organic sheet compositions containing fabric reinforcements, which are usually adhered to the membrane by an adhesive of the manufacturer's specification.
The advantages of the solid concrete slabs or stepping stones are: (1) low cost, (2) durability, and (3) preclusion of adhesive for bonding to the membrane. The disadvantages are: (1) difficulty of handling, (2) difficulty in elevating onto the roof, and (3) necessity of protecting the roof membrane by laying thereon one or more additional sheets of membrane material under the stepping stones.
Another disadvantage in the use of stepping stones of the prior art type is the necessity of separating them by at least two inch gaps to enable proper water drainage.
The advantages of the prior art organic composition sheets or pads are: (1) ease of handling, and (2) moderate cost. The disadvantages include: (1) bonding to the membrane with adhesive, (2) low profile (1/2"-1") allowing ballast stone to be kicked or blown onto the pad surface, (3) difficulty of movement to a different location on the roof, (4) long-term degradation by heat and ultra-violet exposure, and (5) the necessity to separate pads by at least two inches for proper drainage.
The objective of this invention, therefore, is to provide an improved roof walkway module or panel which retains the major advantages of the above prior art devices while eliminating their major disadvantages.
In accordance with the present invention, a roof walkway panel is provided which is much easier to handle than solid concrete slabs or stones, does not require gluing to the roof membrane, will not cut or damage the membrane, and is of a permanent non-degradable nature. The walkway panels according to the invention are easily movable to different positions on the roof and can be closely abutted without requiring drainage gaps.
Other features and advantages of the invention will become apparent to those skilled in the art during the course of the following description.